Gear pump and relief valve



n 1940' J. P. JOHNSON GEAR PUMP AND RELIEF VALVE Filed March 17, 1938 2 Sheets-Sheet 1 FOR LNIwK tw wm 7-3 5 =5 June 1940- J. P. JOHNSON GEAR PUMP AND RELIEF VALVE Filed March 1'7, 1938' 2 Sheets-Sheet 2 INVENTOR. JkMEs flfo/wvsa/v Patented June 4, 1940 UNITED STATES PATENT OFFICE 2,202,912 GEAR PUMP AND RELIEF VALVE ration of Ohio Application March 11, 1938, Serial'No. 196,409

1 Claim.

This invention relates to hydraulic pumps and more particularly to the gear type, embodying certain improvements which make it particularly I on line 4-4 in Figure 1 and showing the fluid adaptable for use on aircraft. For low pressures, not exceeding 200 pounds per square inch, the rotary type pump is desirable and examples of its use are with Gyropilot installations and for pressure heating systems.

For higher pressures, however, ranging from 200 to 1500 pounds per square inch, the gear type pump is much more emcient, especially where the operating speed runs from 1000 to 4000 R. P. M.

Pumps of this type are used in the operation of landing gear, flaps, brakes, wing tip floats, turrets,

etc., and most effectively because of their wide range of pressures regardless of engine speeds.

It is, therefore, an object of the present invention to provide a high pressure gear pump capable of high lift, smoothness of" operation, lack of pulsation and ability to develop and operate under whatever pressure is desired regardless of pump speed.

Another object of the present invention is to provide means for maintaining a constant pressure of the discharged fluid irrespective of variation in the pump speed.

Another object of the present invention is to mount the fluid relief means in such a manner that .the direction of rotation of the gear pump may bereversed without dismantling any of the operating parts of the latter.

Another object of the invention is to provide an improved relief valve structure whereby hammering between the valve and its seat is eliminated thereby increasing the life of the pump unit materially.

A further object of the invention is to provide a simple and expedient means for changing the operative position of the relief valve to conform with the direction of rotation of thegear pump.

With the objects above indicated and other objects hereinafter explained in view, my invention consists in the construction and combination of elements hereinafter described and claimed.

Referring 'to the drawings, a

Figure 1 is a longitudinal sectional view taken on line l-| in Figure-2 showing a detail of the pump and relief valve-assembly embodying the present invention.

Figure 2 is a transverse sectional view taken on line 2-2 in Figure l and showing the relief valve in detail.

Figure 3 is a top-fragmentary view of the relief valve cover showing the position of, the relief ports and a portion. broken away to show one of the fluid openings.

Figure 4 is a transverse sectional view taken openings into the pump. Figure 5 isa transverse sectional view taken on line 5-5 in Figure 4 and showing the various fluid passageways.

I Figure 6 is a transverse sectional view taken on line 6-6 in Figure 4 and showing the fluid 10 passageways and the inlet and outlet openings in detail.

Figure 7 is a transverse sectional view taken on line Tl-l in Figure 2 and showing the fluid passageways connected to the fluid openings into 15 the pump.

In the drawings, I haveillustrated one type of gear pump and relief valve embodying the present invention but the specific structure and arrangement are in no manner restrictive, the application 20 v of the invention to other structures being readily recognized by thoseskilled in the particular art.

I have not shown in the drawings of the present case, details of the pump structure, as reference should be had to my copending application, Serial 25 No. 196,692, flled March 18, 1938, wherein the novel features are claimed. For a clear understanding of the complete unit, however, a description of the pump structure will be hereafter set forth. 30

The pump comprises a housing l0, preferably an aluminum casting for lightness, although other suitable material may be used whichhas the desired characteristics. One end of the housing i0 is provided with a flat smooth surface II 35 from which an axial opening l2 extends inwardly therefrom and communicates with an axial opening I3 of smaller diameter, extending inwardly from theopposite end of the housing It] providing a transverse wall It. Positioned below the open- 40 ing I2 is a second opening l5 preferably of the same diameter as the opening H, which likewise, extends inwardly from the flat surface H and communicates with a bore N5 of smaller diameter, but preferably of the same diameter as the open- 45 ing [3, providing a transverse wall I! which forms a continuation of the wall II. The axes of the openings l2 and I3 are coaxial as are the axes of the opening l5 and bore l6, and while spaced apart the respective axes are in parallelism. Fur- 50 thermore, the openings l2 and i5 slightly overlap at their adjacent portions affording communication between the. openings.

The openings l2, l3, l5, and bore 16 are all heavlly lined with a suitably bearing material I9 55 such as bronze which may be inserted in any desirable mannen' However, it is preferable to first cast the bronze insert to the shape desired and then to cast the aluminum material around the insert. By the so-called ram-up casting, it is possible to obtain a rigid union between the insert and cast aluminum and one-in which the insert is of such thickness as to be substantially unaffected by contraction of the aluminum covering due to atmospheric conditions in actual use.

An external gear 20 is positioned within the opening 12 and has its teeth adapted for running engagement with the inner peripheral surface of the bearing material. The gear 20 is provided with axial extensions 2| and 22 which project outwardly on opposite sides and the extension 21 is rotatably mounted in the bearing material adjacent the opening 43. A second external gear 23 is positioned within the opening I5 and has its teeth adapted for running engagement with the inner peripheral surface of the adjacent hearing material. The gear 23 is provided with axial extensions 24 and 25 which project outwardly on opposite sides and the extension 24 is rotatably mounted in the bearing material adjacent the opening IS. The teeth of both gears 20 and 23 are in meshing engagement adjacent the communicating portions of the openings l2 and I5.

A cover member 26 is positioned upon the flat surface II of the housing I!) and detachably connected to the latter by a plurality of bolts 21 and a gasket 28 is disposed between the cover and housing to provide a fluid tight joint. The cover member 26 has axial bores 29 and 30 extending outwardly which are in coaxial alignment with the opening I 3 and bore I6 in the housing. These bores also have inserts or liners of bushing material and in the present instance comprise tubular extensions 3| and- 32 disposed within their respective bores and circumferential integral flanges 33 and 34 at their inner ends, the adjacent peripheral portions of the flanges being flattened at 35 to prevent relative rotation. The extensions 22 and 25 of the gears 20 and 23 are also rotatably mounted in the bushing extensions 3! and 32 respectively and the peripheral edge of the flanges 33 and 34 fit closely within the outer end of the openings l2 and I5, to permit the inner faces to engage the adjacent ends of the gears and to hold the opposite ends of the gears in engagement with the bearing material on the transverse walls l4|1. With this arrangement the gears and their extensions are substantially entirely surrounded by the bearing material and it being of substantial thickness is unaffected by contraction occurring in the aluminum covering due to changes in atmosphere conditions, thereby providing a free running gear mounting.

The cover 28 has a pair of bosses 1I-12 formed integral therewith which project rearwardly on opposite sides in spaced relation. The bosses have interiorly screwthreaded openings 13-14 respectively which extend inwardly from their outer ends and communicate with coaxially aligned openings 15-16 of smaller diameter to provide shoulders 11-18. The cover is further provided with a pair of passageways 1980 arranged upon opposite sides and which are normally non-communicative. The opening 15 of the boss 1| communicates with the passageway 19 while the opening 16 of the boss 12 communicates with the passageway as more clearly shown in Figure 6.

An opening 8| is provided on the inner side of the cover and extends outwardly into commw cation with the passageway 79. An opening is similarly provided on the inner side of t cover but on the diametrically opposite side a extends outwardly into communication with t passageway 80, this arrangement being mc clearly shown in Figures 4 and 7. The housi: I0 is provided with passageways which extei inwardly from the flat surface II and cor municate at their inner ends with the opposi sides of the meshing gears. These passag ways function as inlet and outlet for the flu depending upon the direction of rotation of ti gears and should therefore be of similar area The openings 8|-82 therefore, should align wit the respective passageways in the housing so i to afiord communication between the pum; ing gears and openings 13 and 14 in the bosse the function of these openings as inlet or out let being dependent upon the direction of rota tion of the gears.

The circuit of the fluid is complete in the fore going assembly but the pressure of the dis charged fluid will vary in direct proportion t the speed of the gears. Therefore, when a con stant pressure of the discharged fluid is desirei irrespective the pump speed, a relief valve is in corporated in the structure to obtain the desire result. Relief valves are in a general sense, Oll and well known, but types in use in the past haw embodied certain structural whicl rendered them inefiicient especially when adaptec for aircraft purposes.

In the present instance, a relief valve is embodied of improved construction and which materially increases the efficiency of the pump operation. The cover member 26 is provided with a pair of fluid relief passageways 83-84 of duplicate form which extend diagonally on opposite ageway 83 in which the The outer end of the passageway 83 is interiorly screwthreaded at 85 to receive the screwthreaded extension 86 of a 'plug 81. The plug 81 has a hexagonal head 88 to accommodate a wrench or inner end to freely receive the head or flange 9| of a pin 92 which projects inwardly centrally thereof. A coiled spring 93 encircles the pin 92 and has its outer end disposed within the recess in engagement with the head 9|. The lower portion of the passageway 83 has a portion 94 of slightly smaller diameter to provide a shoulder 95 and secured within the portion 94 is a tubular bushing member 99 having a laterally extendingflange 91 at its inner end in engagement with the shoulder 95, the inner end of the tubular member being formed as a valve seat 98. A valve member 99 has a valve head I 00 provided with an inwardly tapered surface engageable with the valve seat and an inwardly extending axial projection Illl The inner end of the spring 93 encircles the projection HH and is in engagement with the adjacent face of the valve head for normally urging said valve head into engagement with its valve seat. The tension of the spring 7| may be varied in any desirable manner but in- .tom of the recess the present instance shims (not shown) may be positioned between the head I and the bot- 00. The valve 'member 80 is further provided with a depending tubular extension I02 which is slidably mounted in the tubular member 00 and'a plurality of transversely extending openings I00 are provided in the tubular extension I0! a considerable distance below the valve seat. tioned so that the fluid which enters the open end ofthe tubular extension I02 and raises the valve head from relatively a sufficient distance before the fluid s through the openings I03 so that there is no possibility of hammering therebetween thus increasing the efllciency and life of the pump assembly materially. The open end of the nected by a passageway I04 with the passageway 80 while the lower end of the relief passageway 04 is connected by a similar passageway I05 with the passageway 10. When the drive gear 20 is rotated in the direction of the arrows shown on theviews, suction is created in the passageway causing the fluid to be drawn in through the opening 13, being instance; The incoming fluid passes through the opening 8I of the cover into the inlet opening of the pump housing and to the inlet side of the rotating gears. Here it is forced around the gears and discharged at high pressure from the outlet side of the gears where it flows through the out-" let opening in the housing, through the opening 82 in thecover, into the passageway 80 and out through the outlet opening 14 where it is conveyed by suitable conduit to the instrumentalities which it is to actuate. To insure that the pressure of the discharged fluid 'will be substantially constant, excess fluid from the passageway 80 flows downwardly through the passageway I04 and into the open end of the valve member. The pressure of the fluid raises the valve member off its seat so that the fluid may flow thereby after the valve member has moved suiiiciently to'expose the openings I03 thereby permitting the fluid topass outwardly and to be discharged into the relief valve passageway 84 where it returns to the inlet opening 19 through passageway I05.

The open end of the relief valve passageway 84 is normally closed by a screwthreaded plug I06 in sealing relation and when it is desired to in the direction opposite to that indicated and described, the respective plugs 81 and I06 are removed and interchanged, the valve member, spring,- and pin being assembled in the relief valve passageway 84 in the identical relation as that heretofore described. With this rearrangement the function of the openings and passageways is reversed, that is, those that were the inlet are now outlet and those that were the outlet are now the inlet. It will be further noted that ture an opening I01 is provided in the cover 26 for connecting the end of the bore 20 with the inlet side of the pump for a purpose to be later described.

To adapt the tion with pipes or conduits of different sizes, an interiorly screwthreaded adaptor I08 is provided which has a lateral flange within each of the threaded openings 18 and 14 and seating. upon the shoulder 11. The adaptor has a hollow extension which flts snugly within These openings are posi-- its seat will move the valve head for positive rotation valve member is conrunning fit with the inlet opening in this circular flange 5| adapted present instance in the present strucrelief valve cover 20 for connec- I08 removably fitting 3 the opening 10. A locknut IIO encircles the adaptor and has an extension III exteriorly screwthreaded which' cooperates with the threaded opening 13 and'has its lower end se-'v flange I08.-

curely engaging the upper face of the The nut III is provided with a hexagonal head 8 I I! to accommodate a wrench or other tool. The adaptor is removable and replaceable with similar adaptors having different threaded openings.

The gear 20 may be driven by any suitable means but preferably a drive shaft 40 of steel, is provided which has a splined outer end 4I adapted for connection with the aircraft engine therefrom. The shaft extends through the end of the housing and has a transverse projection 42 upon its inner end which slidably flts within transversely aligned recesses 44 provided in the adjacent end of the extension 2|. 'Outwardly of the projection 42 the shaft 40 is provided with an enlarged circular portion 44a which is disposed within and has a close the inner peripheral surface of the bearing material adjacent the opening I3. The inner face of the enlarged circular portion 44a is spaced slightly from the outer end of the 46 of smaller diameter than that of the flange 45 and positioned outwardly of the latter. An inherently rigid disc 41 of bronze or other bearing material, isdisposed outwardly of the flange 45 and has acentralopening through which the enlarged portion 46 of the drive shaft freely extends. A flexible disc 48 of duprene and fabric or other similar material, is disposed outwardly of the disc 41 and housed within a circular recess 49 provided upon the inner side of an end plate 50. The end plate 50 has an inwardly extending to fit closely within a recessed opening in the adjacent end of the housing and is detachably connected to the latter by a plurality of screws 52. A gasket 53 is disposed at the outer marginal portion between the end plate 50 and the adjacent portion of the housing to provide a fluid tight joint. The discs 41 and 48 are secured to the end plate-50 in any suitable manner to prevent rotation and in the have aligned openings to receive the free end of a pin 54 which-has its opposite end rigidly connected to the -end ,plate as more clearly shown in Figure 1., As many of these pins maybe employed as desired, so as to maintain the discs in proper relation. The machined surface of the flange 45 has a running engagement with the adjacent surface of the disc 41 and the flange is forced into sealing engagement with the disc 41 by the pressure created within the pump housing during operation. The flexible disc 48 is provided to compensate for any misalignment of the drive shaft 40 without affecting the emciency of the seal contact between the flange 45 and disc 41.

It will 'be appreciated that in view of the fact that the pressure within the pump increases tremendously and in direct proportion to the speed of the gears, it would be unsafe and injurious to jected to such time.

high pressures for any length of Furthermor the effectiveness of the'seal can be maintained with relatively less pressure and to accomplish this result means is provided for bleeding the oil from adjacent the seal and returning it to the inletside of the pump. In the present instance the drive gear 26 is provided with an axial opening extending entirely through it and its extensions. This opening is of large diameter at and communicates with a portion 56 of smaller diameter at its inner end forming a shoulder 51. The opening has a portion 68 of smaller diameter than the portion 56 thus providing a shoulder 59. The opening has a further portion 60 of smaller diameter than the adjacent portion 58 thereby providing a shoulder 6| at its inner end, the outer and communicating with the adjacent end of the bore 29 in the cover 26. A tubular member 62 is secured within the portion 56 of the opening and seats against the shoulder 59, its inner end providing a valve seat. A ball valve member 63 is movably mounted in the portion 58 of the opening and engageable with the valve seat. A coiled spring 66 has one end engageable with the ball valve member 63 and its other end engageable with the shoulder 6! to normally maintain the valve member in engagement with its valve seat. A second coiled spring 65 is disposed within the portion 55 of the.

opening and has one end in engagement with the transverse projection 42 on the inner end of the drive shaft while its opposite end is in engagement with the shoulder 56 and the adjacent end of the tubular member 59 are normally urging the flange 45 into sealing engagement with the disc 41.

The tension of the coiled springs is predetermined sothat the pressure exerted by the spring 65 and the pressure of the oil retained adjacent the seal is the effective sealing pressure, the excess oil passing through the opening 55, the opening in the tubular member 5! thereby unseating the valve member 63 and permitting flow through the portions 58 and 66 of the opening where it discharges into the bore. 29 or the cover.

The cover 26 is provided with a passageway I01 communicating with the bore 29 and the inlet opening 36 so that the oil discharged into the bore 29 is returned to the inlet opening. The gear 23v and its extensions may also be provided with an axial opening 6'! therethrough and having its outer end connecting with the bore "of the cover 26 whereby any oil may be discharged therefrom into the-bore 30 and ultimately to the inlet ope ing 36.

The housing has a squared flange 66 formed integral with the end adjacent the drive shaft provided for-draining any oil which might enter from the engine.

extending entirely 7 It is believed that a detailed description or the operation of the pump will not be necessary in view 01' the foregoing descriptio While I have described the preferred embodi- JAMES P. JOHNSON. w 

